This relates to imaging systems and, more particularly, to imaging systems that produce images with fixed output sizes and at constant frame rates.
Modern electronic devices such as cellular telephones, cameras, and computers often use digital image sensors. Imagers (i.e., image sensors) may be formed from a two-dimensional array of image sensing pixels. Each pixel receives incident photons (light) and converts the photons into electrical signals. Image sensors are sometimes designed to provide images to electronic devices using a Joint Photographic Experts Group (JPEG) format.
Some electronic devices have fixed memory allocations and require that JPEG images from image sensors have a fixed size and be provided at a particular frame rate. In order to provide a JPEG image having a fixed size for an electronic device, an image encoder adds padding data at the end of a JPEG data stream during a vertical blanking period for the JPEG image. However, the vertical blanking period for each JPEG image does not always provide enough time for transmission of sufficient padding data (i.e., enough padding data that the size of the JPEG image reaches the required fixed size) and the transmission of the padding data sometimes extends into a subsequent frame, thereby resulting in the dropping of the subsequent image (i.e., resulting in the dropping of an image frame and a deviation from the required frame rate).
It would therefore be desirable to provide improved imaging systems that produce output data streams having fixed output sizes and constant frame rates.